"I use maps to find out where explorers have already been. Then I go the other way."
A Pauper version of Mono-Blue Tron - use counter/bounce spells to control the opponent's board, while building up massive amounts of mana to cast big Eldrazi threats.
Tron
Make Urzatron with Urza's Mine, Urza's Power Plant, Urza's Tower and cast a bunch of expensive spells.
Prophetic Prism as a cantrip that can also filter colorless into blue mana.
Eldrazi
Wretched Gryff as the namesake of the deck - can be cast with tron or a reduced cost with its Emerge ability. It flies, draws a card, avoids Lightning Bolt - everything about this card is great.
Eldrazi Devastator for a big trampler (that avoids double Flame Slash). I actually prefer this over...
Ulamog's Crusher as the classic Pauper win condition - still great.
Other Creatures
Mulldrifter for another flying threat that also draws cards.
Sea Gate Oracle for a deck filtering effect. Can also be sacrificed to Wretched Gryff to make it cost a mere 3 mana (allowing Oracle and Gryff to both be cast for less than the regular cost of Gryff - that's some big time value).
Spells
Repeal for a bounce spell with a cantrip.
Condescend for a counterspell that opponents (hopefully) can't pay for, with a Scry 2 as a bonus.
Miscalculation for a counterspell that opponents (hopefully) can't pay for, with cycling for late game.
Sideboard
Annul for a cheap counterspell against Bogles/Affinity.
Dispel for a cheap counterspell against burn/other instants.
Hydroblast for countering red spells/destroying red permanents - usually bringing in all 4 post-board against anything with red.
Negate for another counterspell option.
Vapor Snag for a cheap bounce spell that also causes a life loss.
Relic of Progenitus for graveyard hate.
Maybeboard
Impulse
for digging through the deck to find whatever you need at the time.
Scour from Existence for an expensive spell that removes any problematic permanent.